Deep imaging of high redshift QSO fields below the Lyman limit. II - Number counts and colors of field galaxies
Deep imaging of high redshift QSO fields below the Lyman limit. II - Number counts and colors of field galaxies
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低于莱曼极限的高红移 QSO 场的深度成像。
DOI：
10.1086/116579
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
D. Hamilton
中科院分区：
文献类型：
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作者：
C. Steidel;D. Hamilton
我们分析了银河系两个高纬度、极高红移类星体中约26.5 MAG的暗星系的数量和颜色。我们集中在微弱星等的场星系的一般性质上。特别是，我们重新讨论了暗星系的数量和颜色作为视星等的函数，并重新审查了极高红移星系对暗样本的可能贡献。我们发现，在R=26的范围内，G带计数符合logN(M)=0.31R+C的关系。同一星系的G带计数在相同的斜率下是一致的，比G弱约23.5，但在较亮的星等处表现出更陡峭的斜率。在R=25.5时，微分数计数已达到1.2×10exp5/sq deg；在G=26.5时，达到了相同的星系面密度。我们证实，外场星系存在逐渐变蓝的趋势，趋向于更暗的视星等；然而，变蓝的趋势似乎只持续到G约24，比(G-R)和(U-N-G)颜色似乎都稳定的更弱。暗星系的平均颜色比平坦的光谱要红得多。对于R=26，基本上没有具有比平坦光谱更蓝的光谱能量分布的物体。在以前的分析中，极高红移星系的潜在贡献可能被低估了；目前的数据与z约为3的相对明亮星系的数量一致，而在z约为0.7的情况下也是如此。
We present an analysis of the number counts and colors of faint galaxies to about 26.5 mag in the fields of two high Galactic latitude, very-high-redshift QSOs. We concentrate on the general properties of the field galaxies at faint magnitudes. In particular, we readdress the faint galaxy number counts and colors as a function of apparent magnitude and we reexamine the possible contribution of very-high-redshift galaxies to the faint samples. We find that the number counts to R = 26 are well fitted by the relation log N(m) = 0.31R + C. The G-band counts for the same galaxies are consistent with the same slope fainter than G about 23.5, but exhibit a much steeper slope at brighter magnitudes. At R = 25.5, the differential number counts have reached about 1.2 x 10 exp 5/sq deg; the same surface density of galaxies is reached at G = 26.5. We confirm the existence of a gradual 'blueing' trend of the field galaxies toward fainter apparent magnitude; however, the blueing trend appears to extend only as faint as G about 24, fainter than which both the (G-R) and (U sub n-G) colors appear to level off. The mean colors of faint galaxies are considerably redder than flat spectrum. There are essentially no objects to R = 26 which have spectral energy distributions which are bluer than flat spectrum. The potential contribution of very-high-redshift galaxies may have been underestimated in previous analyses; the current data are consistent with the same population of relatively luminous galaxies at z about 3 as exist at z about 0.7.